Fluorescein isothiocyanate-doped conjugated polymer nanoparticles for two-photon ratiometric fluorescent imaging of intracellular pH fluctuations

Xiaohui Wang; Yuanxiangyi Feng; Jinhua Liu; Kun Cheng; Yuanan Liu; Wei Yang; Hongxin Zhang; Hongshang Peng

doi:10.1016/j.saa.2021.120477

Fluorescein isothiocyanate-doped conjugated polymer nanoparticles for two-photon ratiometric fluorescent imaging of intracellular pH fluctuations

Spectrochim Acta A Mol Biomol Spectrosc. 2022 Feb 15;267(Pt 1):120477. doi: 10.1016/j.saa.2021.120477. Epub 2021 Oct 12.

Authors

Xiaohui Wang¹, Yuanxiangyi Feng², Jinhua Liu³, Kun Cheng², Yuanan Liu², Wei Yang², Hongxin Zhang², Hongshang Peng⁴

Affiliations

¹ Beijing Key laboratory of Work Safety Intelligent Monitoring, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China. Electronic address: wangxiaohui@bupt.edu.cn.
² Beijing Key laboratory of Work Safety Intelligent Monitoring, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China.
³ Department of Pulmonary and Critical Care Medicine, The Third Hospital of Changsha, Changsha 410015, China.
⁴ School of Science, Minzu University of China, Beijing 100081, China. Electronic address: hshpeng@muc.edu.cn.

PMID: 34662780
DOI: 10.1016/j.saa.2021.120477

Abstract

Herein, we report a two-photon ratiometric fluorescent pH nanosensor based on conjugated polymer poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) nanoparticles loaded with pH-sensitive fluorescein isothiocyanate (FITC) for intracellular pH monitoring. The obtained nanosensor (FITC-PFO NPs) possesses high sensitivity, excellent stability, good reversibility, favorable two-photon excitability and low cytotoxicity. The ratiometric fluorescence of FITC and PFO (F₅₁₇/F₄₁₇) in FITC-PFO NPs solution shows an efficient pH-sensitive response over the pH range from 3 to 10 (pKa = 6.43) under two-photon excitation. Additionally, the FITC-PFO NPs is successfully applied for ratiometric imaging of intracellular pH and its fluctuation in both one-photon and two-photon excitation modes. Overall, the two-photon pH nanosensor based on FITC-PFO NPs exhibits great potential in crucial physiological and biological processes related to intracellular pH fluctuations.

Keywords: Conjugated polymer nanoparticle; FITC; Intracellular imaging; Two-photon excitation; pH sensor.

MeSH terms

Fluorescein
Fluorescein-5-isothiocyanate
Fluorescent Dyes
Hydrogen-Ion Concentration
Isothiocyanates
Nanoparticles*
Polymers*

Substances

Fluorescent Dyes
Isothiocyanates
Polymers
Fluorescein-5-isothiocyanate
Fluorescein